This application claims benefits of Japanese Patent Application No. 2006-137412 filed on May 17, 2006, the contents of which are incorporated by the references.
The present invention relates to a substrate transportation method and apparatus, more specifically to a method and an apparatus for transporting a substrate such as a glass plate to be used in fabrication of an electronic device such as a liquid crystal display panel (LCD), a semiconductor integrated device (IC) or the like from one location to another while removing dust or any other foreign materials attached to or collected on the back surface of such substrate.
Electronic devices such as color liquid crystal display panels or the like are generally fabricated through a series of fabrication steps such as masking, photo lithography, etching, bonding and the like for fabricating on the front surface of such substrate semiconductor devices that drive pixels of such display devices. For this end, a substrate is automatically transported by a substrate transportation apparatus from one location to another in the fabrication process of such electronic devices. Such substrate becomes increasingly larger in size as the display device becomes larger and also for the purpose of reducing production cost per device.
In such electronic devices, attachment of dust or any other foreign materials on the surface of such substrate results in defective pixels or semiconductor devices for driving such pixels, thereby determining quality, production yield (or productivity), production cost and the like of the fabricated electronic device. Accordingly, in order to improve productivity and production cost of such electronic device, it is essential to prevent dust or any other foreign materials from attaching to the substrate surface or to minimize dust or any other foreign materials on the substrate surface.
A main cause of collecting dust or any other foreign materials on the surface of the substrate for such electronic device is understood to be transportation of such substrate from one place to another in the fabrication process. If dust or any other foreign materials attaches on the substrate surface during transportation, such dust or any other foreign materials attaches to the surface of adjacent substrate when they are stacked. It is therefore desirable to develop a substrate transportation method and apparatus capable of transporting a substrate to be used for fabrication of electronic devices so that no dust or any other foreign materials attach to the surface of the substrate under transportation.
There are some publications disclosing conventional technologies of transporting a substrate while preventing dust or any other foreign materials from attaching to the substrate surface or minimizing dust or any other foreign materials on the substrate surface. For example, Japanese patent publication no. 2000-15187 discloses a foreign material removing apparatus for transporting a substrate on transportation rollers, in which foreign materials attached to the bottom surface of such substrate are wiped off by a first rotary brush, a second rotary brush is disposed below the first rotary brush for knocking for more completely removing foreign materials attached to the substrate.
Japanese patent publication no. 2002-22359 discloses a dryer for spraying air knife onto the bottom surface of a substrate that is being transported on transportation roller for removing liquid attached to the substrate, thereby drying the substrate. Moreover, Japanese patent publication no. 2003-229404 discloses a substrate processing apparatus for sucking mist from a substrate surface and also exhausting such mist for preventing it from attaching to the substrate when the substrate passes through upper and lower air knives in a substrate transportation path, thereby improving substrate processing quality. Additionally, Japanese patent publication no. 7-14819 discloses a substrate dryer in which a down-flow is generated in a substrate drying process by an air knife in a clean unit for exhausting impurities from an outlet, thereby preventing such impurities from attaching to the substrate.
However, such conventional technologies as described hereinabove require relatively complicated, bulky and expensive apparatus for removing dust or any other foreign materials from the bottom surface of the substrate. It is also difficult to effectively remove foreign materials from the substrate under transportation.